Piezo-electric crystal holder



g- 1940- w. SCHNEIDER PIEZO-ELECTRIC CRYSTAL HOLDER Filed Oct. 20, 1938QUARTZ CRYSTAL Y mmgm T5 .W M A Patented Aug. 6, 1940 UNITED STATESPATENT OFFWE PIEZO-ELECTRIO CRYSTAL HOLDER.

tion of Germany Application October 20, 1933, Serial No. 235,928 InGermany October 30, 1937 7 Claims.

This invention relates to a novel supporting or mounting forpiezoelectric oscillator crystals. It concerns more particularly themode of accommodating two crystals inside a minimum amount of space. Anarrangement of this kind is useful to particularly great advantage inheterodyne sets in which two piezoelectric crystals are to oscillate atdifferent frequencies in such a way as to result in as stable asfeasible a frequency difference. In order to secure a steady and stablefrequency difference it is advantageous to mount the two crystals undersimilar conditions and at the greatest possible proximity to each other,while taking care so that they are subject to the identical externalconditions as to temperature, etc.

The object of the invention satisfies these requirements, while itsolves at the same time the problem of holding or mounting the crystalsinside a minimum space.

A feature of this invention is a twin crystal mounted in a casecomprising two ceramic cups or shells comprising a central electrodecommon to both oscillator crystals and adjustable external electrodes.

The invention shall be described more fully by reference to the appendeddrawing. The single.

figure is a sectional view of an embodiment of my invention. The ceramiccups or shells I support the electrodes 3 adjustably held in the bushesor sleeves 2. The central electrode 4 has a peripheral enlargement 5 ofannular form, and the inner circumference thereof has screw-threads cuttherein upon both sides. Screwed into these screw-threads are thesupporting rings 6; by the aid of clamp screws 7 they may be locked in adefinite position. In the holder rings 6 are held the quartz crystals 8by the agency of screws 9. By rotation of the said holder rings in theirscrew-threads they may be looked a certain distance from the centralelectrode. The outer parts of the mounting l, 2 and 3 referred to aboveare secured by screws iii on the holder rings 6, and this insures astable and dependable union and assembly of all constituent parts.

A special merit of the invention as described is that the oscillationcrystals individually are settable in reference to the centralelectrode, as well as that the outer electrodes are adjustableindividually without it being necessary to demount the device to thisend. In fact, to set the crystals in relation to the central electrodeall that is necessary is to loosen the clamp screw 1 in order to allowturning the entire top part comprising crystal, holder rings, ceramicshells and external electrode whereby the distance between the crystaland the median electrode is altered. The adjustment of the outerelectrodes 3 is effected by rotation of the screw-threads of bushes 2.It will thus be noted that the setting of the inter-electrode 5distances is feasible under conditions independent of each other,without incidentally the adjustment of one electrode distance affectingthat of the other in any way.

It will be understood that in lieu of an arrange- 10 ment comprisingholder rings being adjustable in reference to the central electrode itis also possible to resort to a simplified embodiment in which theholder rings are fitted firmly upon the median electrode and are screwedtogether therewith. 16

What is claimed is:

1. Holder or mounting for two piezoelectric vibratory or oscillatorycrystals, with the characteristic feature that a central electrodecommon to both quartz crystals is provided which has an an- 20 nularenlargement in which are screwed the rings serving for holding thequartz.

2. Twin crystal mounting or holder as claimed in claim 1, with thecharacteristic feature that the distance between each of the crystalsand the 25 middle electrode is individually and separately adjustable byrotation of the crystal mounting ring in the screw-thread of the middleelectrode.

3. Twin-crystal mounting or holder as claimed in claim 1, with thecharacteristic feature that 30 held on the crystal holder ring by meansof screws upon each side thereof is a ceramic half-shell or cup in whichthe outer electrode is adjustably mounted.

4. A holder for a pair of piezoelectric crystals 35 comprising a centralelectrode having an annular rim, crystal holding rings in individualadjustable relationship with said rim whereby the spacing between saidcentral electrode and each of the crystals carried by said rings may beindependently adjusted, insulating cups carried by each of said ringsand outer electrodes adjustably carried by said cups.

5. A holder for a pair of piezoelectric crystals comprising a centralelectrode having an annular 45 rim, said rim being screw-threaded on itsinner surface, crystal holder rings in threaded engagement with saidrings, said rings being individually adjustable along said rim wherebythe spacing between said central electrode and each of the crystalscarried by said rings may be independently adjusted, insulating cupscarried by each of said rings and outer electrodes adjustably carried bysaid cups.

6. A holder for a pair of piezoelectric crystals comprising a centralelectrode having an annular rim, said rim being screw-threaded on itsinner surface, crystal hold-er ringsin threaded engagement with saidrings, said rings being individually adjustable along said rim wherebythe spacing between said central electrode and each of the crystalscarried by said rings may be independently adjusted, insulating cupscarried by each of said rings and outer electrodes within each of saidcups and threaded means for varying the spacing between each of saidcrystals and its adjustable outer electrode.

7. A holder for a pair of piezoelectric crystals comp-rising a centralelectrode having an annular rim, said rim being screw-threaded on its inner surface, crystal holder rings in threaded engagement with saidrings, said rings being individ ually adjustable along said rim wherebythe spacing between said central electrode and each of the crystalscarried by said rings may be independently adjusted, insulating cupscarried by each of said rings, a threaded bushing in each of said cupsand outer electrodes having threaded shanks engaged in said bushingswhereby each of said outer electrodes may be adjustably positioned withrespect to its adjacent crystal.

TlLI-IELM SCHNEIDER.

